BMP: Introduction to Lipids Flashcards
What is a Lipid?
A biological molecule soluble in an organic solvent (e.g. ethanol, hexane)
What is a fat?
A fat is a moleulce which is solid at room temperature and is soluble in an organic solvent
What is an oil?
A molecule which is liquid at room temperature and soluble in an organci solvent
What are the 4 main functions of lipids in the body?
- Some vitamins are lipids or lipid derrivatives
- Some act as an energy reserve and providr insulation
- Some are stuctural elements of biological membrane
- Some (e.g. bile acids) help to solublize other lipids during digestion
What is the general structure of a lipid?
Polar hydrophillic head and hydrophobic non-polar tail
What is a special property of lipids?
- They are amphipathic - have both hydrophillic and hydrophobic components
What different structures/ arrangements of lipids are possible?
- Monolayer
- Micelles
- Bilayer: membrane
How is a micelle formed?
Vigourous mixing of water/lipid layer
What properties are there of a bilayer? What forces occur?
- Polar heads heavily hydrated
- hydrophibic tails arranged roughly parralel
- Interaction is van der waal forces
What types of lipids is there?
- Fatty Acids
- Triglycerides
- Phospholipids
- Sphingolipids
- Phosphoglycerides
- Glycosphingolipids
- Cholesterol
- Bile acids
- Steriod hormones
What are Fatty acids?
Hydrocarbon chains with a terminal carboxylic acid group
- Is FA an acid or a base? Why?
- What happens at physiological pH?
- Weak acid due to the carboxylic acid group
- As its pKa is arounf 4.5, at physiological pH (7.4) it is ionised and amphipathic)
What can be said about the hydrocarbon chains or FA?
- Can vary in length but long chained (16-18C) most common
- Vary in satuartion:
- Saturated:
- Stearic acid (18:0)
- Capric acid
- Palmitic acid
- Monounsaturated:
- Oleic acid (18:1)
- Polyunsaturated:
- Linoleic acid (18:2/3)
- Arachidonic acid (20:4)
- Saturated:
What is the configuration around double bonds in FAs? why is this important?
Normally cis.
Each cis double bond exerts a bend in the hydrocarbon chain
What do the FA triglcerides function as?
Act as insulation
Act as an energy reserve
- What are essential FAs?
- Give examples
- Why are these important
- FAs which can’t be synthesised in the body and must be obtained from the diet
- Linoleic and linolenic acid
- Important in infant development
How do lipids travel in the body? Why?
Low solubility therefore carried in blood by albumin - plasma protein
- What is the difference in FAs as an energy source comparered to proteins and carbohydarates
- What can FA be used for?
- Are FA present in the tissues?
- Provide more E
- Precursors for other lipids
- low levels
What are triglycerides?
What are they also known as?
What FAs can be used?
- Fats
- Glycerol molecule covaently bonded by an ester linkage to 3 FAs
- All the same or different
How do natural fats melt and why?
over a broad range due to having a range of triglycerides
Where are triglycerides generally stored?
What is the function of this cell?
- cytoplasm of adipose cells
- Specialised in the synthesis and storage of TGs and mobilisation into fuel moeulces which are transported to tissues in the blood
What are lipid constiturnts of biological membranes?
- Polar, ionic compound composed of an alcohol attached by a phosphodiester bridge to either diacyliglycerol or sphingosine
What are the properties of a phopholipid and what it consists of
Where does the lipid interact with in the membrane
- amphipathic
- Polar head = phosphate group and whatever attachec
- hydrophobic tail = hydrocarbon tai
- hydrophobic part assoicates with non-polar regions of membranen e.g. cholsetol, proteins, glycolipids and sphingosine
What is the structure of a phosphoglyceride like?
Where are these structures found?
•Are the major class of phospholipids which make up a large proportion of the membrane in mammals, bacteria and plants
How does the naming system work if the alcohol attached is the following
- Serine
- Choline
- Ethanolamine
- Glycerol
- Inositol
- Serine “ Phosphatidylserine
- Choline “ Phosphatidylcholine
- Ethanolamine “ Phoshatidylethanolamine
- Glycerol “ Phosptidylglycerol
- Inositol “ Phospatidylinositol
What are sphingolipids
- Are not derived from glycerol
- Backbone of sphingolipids is sphingosine, an amino alcohol that contains a long, unsaturated hydrocarbon tail
What are types of sphingolipids?
- If a fatty acid is linked via an amide bond to the amino group of sphingosine, a ceramide is obtained.
- Further additions to the hydroxyl group leads to a variety of other membrane lipids:
–One important example is sphingomyelin, which is highly concentrated in the brain and nervous tissue.
In sphingomyelin one hydroxyl
What are glycosphingolipids
- •In glycosphingolipids, the alcohol group of sphingosine is attached to one or more sugar molecules, usually glucose or galactose.
- •Note that they do no contain phosphate and therefore are not classed as phospholipids.
- •The simplest glycosphingolipids are Cerebrosides – in which there is only one sugar molecule attached
- These are usually found in brain and neuronal tissue
- More complex glycolipids, such as gangliosides, contain a branched chain of up to 7 sugar residues.
- These are normally found in nerve tissue.
What is cholesterol
- Cholesterol is a member of a large group of substance called steroids.
- A steroidal compound contains a fused ring system, labelled A, B, C and D.
- Cholesterol is incorporated into cell membranes as it gives them rigidity.
What are eamples of cholestrol derivatives
- Steroid hormones
- Sex steroid hormones
- e.g. progesterone, tesosterone
- Mineralocoritcoids:
- aldosterone
- Coricosteriods
- Cortisol
- Sex steroid hormones
- Bile salts
- Polar derivatives of cholesterol
- Act as detergents in the small intestine to aid digestion of fats
- The major mammalian bile salt is glycocholate:
